Lithium alkoxides bridge the gaps between organic and inorganic chemistry and are growing increasingly important. Lithium alkoxides are useful as catalysts for a wide variety of polymerization reactions and for esterifications, condensation and isomerization processes, for example, the preparation of lithium ethylene glycoxide by adding a stoichiometric amount of lithium t-butoxide to excess ethylene glycol.
The lithium alkoxides are generally prepared from lithium metal and an excess of the parent alcohol and sold in their pure or purified form to be dissolved in the solvent used for a selected reaction. However, isolation and purification for subsequent use increases the cost of the catalyst. Moreover, subsequent dissolution in solvents for the reaction has generally required the use of a large amount of solvent in order to obtain a sufficient amount of catalyst in solution to obtain a desired yield. It therefore would be advantageous to prepare a catalyst reagent composition which does not require isolation and/or purification of the catalyst and wherein the reagent composition can be used directly in a desired reaction. It is even more preferable if the reagent composition contains a high concentration of the catalyst and a minimal excess of alcohol.
Lithium t-butoxide is a popular compound for use in metalation and as a catalyst in organic synthesis. It is moderately soluble in hydrocarbon synthesis, e.g. about 1.35M in toluene. In fact, it is only soluble at about 2.3M in tetrahydrofuran which is its best solvent. However, in metalation reactions better yields can be obtained with high concentrations of lithium alkoxides.
When using a concentrated solution of lithium alkoxides, it is desirable to use concentrated solutions to minimize the amount of additional solvents being added to the reactor.
U.S. Pat No. 3,761,529 discloses a method of purifying lithium alkoxides which are prepared from lithium metal wire and an excess of alcohol in tetrahydrofuran. The objective of the patent is to prepare and then isolate the lithium alkoxides. One of the problems in the process disclosed is that the presence of a large excess of alcohol reduces the solubility of the alkoxide prepared and contributes to the presence of impurities.
It is an object of the invention to provide a means for making available high concentrations of lithium alkoxides for use in reactions.
It is a further object of the invention to provide lithium alkoxide in solution.
It is a yet further object to provide increased concentrations of lithium alkoxides in ether--free solvents.